Localized diffuse-type gastric adenocarcinoma: Influence of baseline positron emission tomography on survival and therapy response.

Abstract

176 Background: Diffuse type of gastric adenocarcinoma (dGAC) confers a poor but variable prognosis compared to intestinal type of GAC. The value of baseline uptake of FDG-PET in localized dGAC is unclear and ~40% are not FDG-PET avid. We analyzed outcomes based on the avidity (high with SUV > 3.5 or low with SUV ≤3.5) of the primary on baseline FDG-PET. Methods: We retrospectively selected 111 localized dGAC cases who had baseline FDG-PET for staging. We compared the FDG-PET avidity with overall survival (OS) and response to preoperative therapy. Standard statistical methods were utilized. Results: The mean age was 59.4 years and with many female patients (47.7%). All patients had dGAC. The high-SUV group (58 [52.3%] patients) and the low-SUV group (53 [47.7%] patients) were equally divided. While the median OS for all patients was 49.5 months (95% CI: 38.5 – 98.8 months), it was 98.0 months for the low-SUV group and 36.0 months for the high-SUV ( p value = 0.003). While the median PFS for all patients was 38.2 months (95%CI: 27.7 – 97.6 months), it was 98.0 months for the low-SUV group was and 27.0 months for the high-SUV group ( p value = 0.005). Clinical responses before surgery were more common in the low-SUV group but there were only 4 patients with pathologic complete response in the entire cohort. Conclusions: Our unique data suggest that localized dGAC patients with low SUV fare better than those with high SUV meaning highly metabolic GACs consuming glucose confer poor prognosis and overall all dGACs seem resistant to therapy.